1. Field of the Invention
This invention relates to vacuum cleaner structures and in particular to control means for use therein.
2. Description of the Prior Art
In one conventional vacuum cleaner system, a floor cleaning unit is provided with a handle for movement thereof over the floor to be cleaned. The floor cleaning unit is connected through wand handle sections and a suction hose to a canister suction unit having means for drawing a vacuum through the suction hose to the floor cleaning unit.
As is conventional, the suction hose may have incorporated therewith electrical conductors for energizing a brush motor provided in the floor cleaning unit without the need for separate wires extending between the canister and floor cleaning unit. On-off control of the vacuum cleaner is conveniently effected by a suitable "On-Off" switch provided on the handle of the hose attached to the canister suction unit.
One example of such a vacuum cleaner structure is illustrated in U.S. Pat. No. 3,588,943 of Thomas E. Hetland, which patent is owned by the assignee hereof. As shown therein, a control is provided in association with the three electrical conductors of the suction hose for selectively operating the suction motor independently of the brush motor and causing the suction motor to run at a preselected reduced speed when operated concurrently with the brush motor. The control requires that whenever the brush motor is energized, the suction motor be energized to operate at a low speed regardless of the total amount of current being utilized by the two motors.
Robert L. Daugherty shows, in U.S. Pat. No. 3,077,542, an electrical control system having means responsive to an overload condition in one circuit for reducing the total effective load of a second circuit as long as the overload condition continues to exist in the first circuit.
In U.S. Pat. No. 3,579,706 of Thomas E. Hetland, which patent is also owned by the assignee hereof, a vacuum cleaner motor control is shown to include a circuit for varying the current to the suction motor, thereby varying the amount of suction applied to the floor cleaning unit. A second switch circuit is provided for energizing the brush motor, when desired. The switch utilized is a double-pole, triple throw switch, involving two switching circuits, one of which controls the speed of the suction motor and the other of which controls the operation of the brush motor.
William T. Wickham et al show, in U.S. Pat. No. 3,636,285, a vacuum cleaner hose assembly having a control device carried by the suction hose with the matrix material of the hose connector providing the sole support of the control device.
Robert N. Brigham shows, in U.S. Pat. No. 4,021,879, a vacuum cleaner structure having means for automatically maintaining the volumetric air flow substantially constant within limits of the capabilities of the system under varying conditions of resistance to such flow. A switch is provided on the handle to start and stop the suction motor, as well as a brush motor in the nozzle of the floor cleaning unit.